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Topic:Biochemistry
The study of biochemistry in horses encompasses the chemical processes and substances that occur within equine organisms. This field investigates the molecular interactions and pathways that are fundamental to horse physiology, including metabolism, enzyme activity, and genetic expression. Key areas of interest include the examination of metabolic disorders, nutrient absorption, and the biochemical basis of muscle function and energy production. Researchers utilize biochemical analysis to understand health and disease mechanisms in horses, contributing to the development of diagnostic tools and therapeutic strategies. This page gathers peer-reviewed studies and scholarly articles that explore various biochemical processes and their implications for equine health and performance.
Antagonistic effects of atipamezole on medetomidine-induced sedation in horses. The antagonistic effects of atipamezole (20, 40, 60, 80, and 100 micrograms/kg i.v.) on medetomidine (10 micrograms/kg i.v.)-induced sedation were evaluated in horses. Although 20 and 40 micrograms/kg of atipamezole were not sufficient to reverse the sedation, 60 micrograms/kg did effectively reverse the sedation. Atipamezole at 80 micrograms/kg was more potent, and significantly shortened the duration of sedation without any apparent side effects, but a higher dose of 100 micrograms/kg was not more effective than 80 micrograms/kg. The possible use of atipamezole as a reversal agent may enhanc...
Myosin heavy chain isoforms in adult equine skeletal muscle: an immunohistochemical and electrophoretic study. The aim of this study was to characterize the myosin heavy chain (MyHC) isoforms present in equine skeletal muscle. Methods: Muscle biopsies were removed from the superficial region of the gluteus medius muscle of five mature horses and analyzed by immunohistochemistry (using a battery of monoclonal antibodies specific for rat MyHC isoforms) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results: Immunohistochemistry allowed subdivision of three different muscle fiber populations containing a single MyHC, one slow and two fast, and two hybrid populations, one containing slow an...
Activation of apical P2U purine receptors permits inhibition of adrenaline-evoked cyclic AMP accumulation in cultured equine sweat gland epithelial cells. Experiments were undertaken using cultured equine sweat gland epithelial cells that express purine receptors belonging to the P2U subclass which allow the selective agonist uridine triphosphate (UTP) to increase the concentration of intracellular free Ca2+ ([Ca2+]i). Experiments using pertussis toxin (Ptx), which inactivates certain guanine-nucleotide-binding proteins (G-proteins), showed that this response consisted of Ptx-sensitive and Ptx-resistant components, and immunochemical analyses of the G-protein alpha subunits present in the cells showed that both Ptx-sensitive (alpha i1-3) and Ptx...
Variability of cardiomyocyte DNA content, ploidy level and nuclear number in mammalian hearts. DNA content, ploidy level, cell size and nuclear number were investigated in 54 mammalian hearts from nine species. DNA content was determined biochemically and ploidy level of cells was studied by the means of Feulgen cytophotometry. Nuclear number was calculated by a new method, while cell size was determined by using ocular micrometry. In most mammals diploid cell nuclei predominate. Higher ploidy levels were found in the human and the pig hearts. The total amount of DNA correlated with the myocardial weight. Eight million heart muscle cell nuclei were found in mice (myocardial weight 160 m...
Excitatory prejunctional beta 2-adrenoceptor distribution within equine airway cholinergic nerves. We examined the effect of activation of beta 2-adrenoceptor (AR) by isoproterenol (ISO) on acetylcholine (ACh) release evoked by electrical field stimulation (EFS: 20 V, 0.5 Hz, 0.5 msec) from cholinergic nerves in five regions of equine airways. We also tested if the effect of ISO was dependent on epithelium or prostanoids by examining the effect of ISO on ACh release in the presence and absence of epithelium or cyclooxygenase inhibition. Trachealis strips or bronchial rings were preincubated for 60 min with 10(-7) M atropine, 10(-6) M neostigmine, and 10(-5) M guanethidine. The ACh amount wa...
Nucleologenesis and ribonucleic acid synthesis in preimplantation equine embryos. The nucleolus is believed to be the active site of rRNA synthesis in all eukaryotic cells. In preimplantation embryos, the embryonic genome is apparently more or less silent up to a species-specific developmental stage at which a major burst of transcription occurs. Here we report on nucleologenesis and some ultrastructural aspects of the onset of RNA synthesis in equine embryos during in vivo development. The zygotes and embryos up to blastocyst stages were surgically recovered from normally cycling mares. Mares were induced to ovulate by treatment with 3000 IU hCG and inseminated 20 and 34 h...
[Enantioselectivity in the excretion of glucuronides of carprofen in man, dogs and horses]. After administration of the racemic drug, the stereoselective quantification of the enantiomers of free and conjugated carprofen was performed in human plasma and in plasma, urine and bile of dogs and horses. In humans, the plasma profile of free carprofen and its glucuronides is not stereoselective and the glucuronides excreted in urine are close to a racemate. In dogs and horses on the contrary, the R(-) enantiomer of the free drug is predominant in plasma, while urine and/or bile concentrations of the glucuronides are high in comparison to plasma with a strong selectivity for the S(+) enant...
Characterization of polypeptides synthesized and secreted by oviductal epithelial cell explants obtained from young, fertile and aged, subfertile mares. To compare the electrophoretic patterns of proteins synthesized and secreted by oviductal epithelial cell (OEC) explants obtained from young, fertile and aged, subfertile mares. Methods: Young, fertile (n = 5; 2 to 7 years old) and aged, subfertile (n = 5; 17 to 24 years old) mares. Methods: 2-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and computerized densitometry. Results: Variation in the synthesis and secretion of polypeptides from young, fertile mare OEC (YOEC) and aged, subfertile mare OEC (AOEC) was evidenced by differences in the intensity of radiolabeled pol...
Equine cytochrome P450 aromatase exhibits an estrogen 2-hydroxylase activity in vitro. Aromatase (estrogen synthetase) is a steroidogenic enzyme complex which catalyzes the conversion of androgens to estrogens (termed aromatization). This enzyme was purified from adult equine testis to homogeneity by five chromatographic steps. The ability of purified and reconstituted equine aromatase to exhibit an estrogen 2-hydroxylase activity was tested and compared to testosterone aromatization. Enzymatic activities were assessed by tritiated water release from labelled estradiol and testosterone. Kinetic analysis of estradiol 2-hydroxylation showed an apparent K(m) of 23 microM and a V(ma...
Daily fluctuations of haematology and blood biochemistry in horses fed varying levels of protein. Changes in the plasma biochemistry of 12 stallions were studied over seven 24 h periods. Twelve healthy male horses of 4 different breeds (Thoroughbred [TB], Anglo-Arabo-Sardo [AAS], Avelignese [Av] and Maremmano [M]) were divided into 3 experimental groups and fed with an isoenergetic maintenance ration with different protein levels. The same amount of food was given daily at 0730 and 1930 h. After 20 days of pretrial, a series of 6 blood samples were collected daily from the jugular vein every 4 h for 7 days. The samples were analysed for packed cell volume (PCV), haemoglobin, plasma glucose...
Maintenance of equine articular cartilage explants in serum-free and serum-supplemented media, compared with that in a commercial supplemented medium. To evaluate the effects of a commercially defined, serum-free medium additive on equine articular cartilage explants, compared with effects of serum-free and serum-supplemented media. Methods: Articular cartilage from a 3-year-old, mixed breed horse euthanatized for reasons other than musculoskeletal disease or sepsis. Methods: Media were changed every 48 hours, and the glycosaminoglycan (GAG) content was determined in media collected at each time point. Glycosaminoglycan synthesis by explant chondrocytes, and residual GAG content of articular cartilage (as a measure of explant GAG loss) were ...
Molecular diffusion into horse spleen ferritin: a nitroxide radical spin probe study. Electron paramagnetic resonance spectroscopy and gel permeation chromatography were employed to study the molecular diffusion of a number of small nitroxide spin probes (approximately 7-9 A diameter) into the central cavity of the iron-storage protein ferritin. Charge and polarity of these radicals play a critical role in the diffusion process. The negatively charged radical 4-carboxy-2,2,6,6-tetramethylpiperidine-N-oxyl (4-carboxy-TEMPO) does not penetrate the cavity whereas the positively charged 4-amino-TEMPO and 3-(aminomethyl)-proxyl radical and polar 4-hydroxy-TEMPO radical do. Unlike th...
Calcium buffering is required to maintain bone stiffness in saline solution. This work determined whether mineral dissolution due to prolonged testing or storage of bone specimens in normal saline would alter their elastic modulus. In one experiment, small pieces of equine third metacarpal bone were soaked in normal saline supplemented with varying amounts of CaCl2. Changing Ca ion concentrations in the bath were monitored and the equilibrium concentration was determined. In a second experiment, the elastic moduli of twenty 4 x 10 x 100 mm equine third metacarpal beams were determined non-destructively in four-point bending. Half the beams were then soaked for 10 days ...
Measurement of bone specific alkaline phosphatase in the horse: a comparison of two techniques. For many years total alkaline phosphatase (AP) activity in serum has been used to monitor bone metabolism in different species. However, total AP lacks bone specificity because the total activity in serum is made up of several isoenzymes, of which the liver and bone isoforms predominate. The aim of the present study was to evaluate an immunoradiometric assay for measuring bone specific alkaline phosphatase (BAP) in horses. BAP, a specific marker of bone formation, was measured in sera from thoroughbred horses by using a previously characterised wheat germ lectin (WGL) precipitation assay and a...
SDS-PAGE characterization of the proteins in equine seminal plasma. The aims of this project were to document the protein profile of equine seminal plasma and determine the variability between stallions in the relative composition of proteins in the ejaculate. A single ejaculate was obtained from 14 stallions of varying breed and age. The gel fraction was removed by an in-line filter. The semen was centrifuged and the supernatant seminal plasma aspirated without disturbing the sperm pellet. The seminal plasma was recentrifuged and stored in cryovials at -70 degrees C. Samples were thawed, recentrifuged, assayed for protein concentration (BCA protein assay), di...
Further characterization of IgE-binding antigens in horse dander, with particular emphasis on glycoprotein allergens. IgE-binding components in an extract of horse dander were analyzed, especially with regard to the glycoprotein allergens. After SDS-PAGE under reducing conditions and blotting, several of the glycoprotein IgE-binding components, including two distinct bands of 27 and 31 kDa, were detected. Together with several other bands, they were shown to bind to the lectins Sambucus nigra agglutinin (SNA) and Datura stramonium agglutinin (DSA), indicating terminal sialic acid linked alpha 2 --> 6 to galactose, and galactose linked beta 1 --> 4 to N-acetylglucosamine, respectively. Carbohydrate analy...
Pharmacokinetics of ketoprofen in the donkey (Equus asinus). The pharmacokinetic parameters of ketoprofen were determined in four donkeys after a single intravenous injection of a dose of 2.2 mg/kg body weight. The total body clearance (ClB) was 414.0 +/- 98.70 ml/h/kg (mean +/- SD), the volume of distribution at steady state (Vss) 263.10 +/- 55.43 ml/kg and the elimination half-life 1.30 +/- 0.75 h. These values were compared to those obtained in horses.
A screening test for subclinical liver disease in horses affected by pyrrolizidine alkaloid toxicosis. To evaluate various biochemical tests as indicators of subclinical liver disease in horses exposed to pyrrolizidine alkaloid toxicosis. Methods: A clinical pathology field study. Methods: Twenty-two clinically normal horses from four properties in the Kimberley region of Western Australia. Methods: Serum samples from each horse were assayed for gamma glutamyltransferase, alkaline phosphatase and aspartate aminotransferase activities, and for serum bile acid concentration, albumin and total protein. Serum protein electrophoresis was performed and their amino acid profiles determined. Bromosulph...
Methanogenesis in monogastric animals. Studies of methanogenic bacteria present in monogastric animals are still scarce. Methanogens have been isolated from faeces of rat, horse, pig, monkey, baboon, rhinoceros, hippopotamus, giant panda, goose, turkey and chicken. The predominant methanogen in all except the chicken and turkey is species of Methanobrevibacterium. The chicken and turkey harbour species of Methanogenium. In pig the population of methanogenic bacteria is more than 30 times as dense in the distal colon as in the caecum. This finding is in agreement with the finding that the rate of methane production is much higher in...
Fibronectin mRNA splice variant in articular cartilage lacks bases encoding the V, III-15, and I-10 protein segments. Fibronectin is an extracellular matrix glycoprotein encoded by a single gene. Alternative RNA splicing has been reported at three sites, ED (extra type III domain)-A, ED-B, and the variable or V region. Articular cartilage fibronectin monomers are rarely (ED-A)+, but approximately 25% are (ED-B)+. RNA gel electrophoresis and Northern blot analysis identified two (ED-B)+ and two (ED-B)- fibronectin transcripts in cartilage, each pair differing by approximately 750 bases. This difference results from a previously unreported RNA splicing pattern that eliminates not only the V region but also nucl...
Gene transfer by adenovirus in smooth muscle cells. We report adenovirus-mediated gene transfer into airway smooth muscle cells in cultured cells and organ-cultured tracheal segments. Incubation of cultured rat tracheal myocytes with virus (5 x 10(8) pfu/ml) for 6 h resulted in beta-galactosidase expression in 94.8 +/- 2.5% of cells (n = 4). Following incubation of thin (less than 200 microns diameter) equine trachealis muscle segments with virus in organ culture (5 x 10(8)-5 x 10(10) pfu/ml) the average expression of the Lac Z gene was approximately 19 +/- 10% (n = 9). Expression was markedly improved, however, in segments from neonatal rats (...
Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin/phosphatidylcholine membranes. Complex formation between horse heart cytochrome c (cyt c) and bovine cytochrome c oxidase (cco) incorporated into a supported planar egg phosphatidylcholine membrane containing varying amounts of cardiolipin (CL) (0-20 mol%) has been studied under low (10 mM) and medium (160 mM) ionic strength conditions by surface plasmon resonance (SPR) spectroscopy. Both specific and nonspecific modes of cyt c binding are observed. The dissociation constant of the specific interaction between cyt c and cco increases from approximately 6.5 microM at low ionic strength to 18 microM at medium ionic strength, ...
Comparison of media and sera used for in vitro culture of equine superficial digital flexor tendon explants. To compare the effects of different commercial nutrient media and sera on protein synthesis and maintenance of cellular density in cultures of the equine superficial digital flexor tendon (SDFT). Methods: 8 healthy 2- to 4-year-old horses. Methods: First Dulbecco's modified Eagle's medium, Ham's F12 nutrient mixture, RPMI 1640 medium, minimum essential medium with Earle's salts, minimum essential medium with Hanks' salts, and a Dulbecco's modified Eagle's medium/Ham's F12 nutrient mixture with 10% fetal bovine serum (FBS) were compared. Then FBS, fetal equine serum, and donor horse serum, each...
[Changes of serum enzymes, lactate and hemoglobin concentrations in the blood of young trotting horses due to training exertion]. Until the age of about 2 years, trotters normally grow up on pasture without any kind of training. In the stud farm Lindenhof (Templin, Germany), however, these first 2 years are used for a special fitness training for the young animals: 2-3 times a week, a group of the yearlings is forced to run a distance of about 1700 m on a track at an average speed of up to 10 m/s. Until now, little was known about changes of blood parameters which may occur during such special exercise. This study therefore investigated the activity of selected serum enzymes (aspartate-amino-transferase (AST), alanine-am...
Biochemical and antigenic relationships between porcine and equine isolates of Actinobacillus suis. A total of 50 Actinobacillus suis isolates were studied for their biochemical and antigenic characteristics. Of them, 40 isolates originated from different tissues of diseased pigs, and the other ten isolates were from horses with respiratory problems. There was no major biochemical difference among equine and porcine A. suis isolates. Results of tube agglutination tests showed that porcines isolates were antigenically homogeneous while equine isolates were heterogeneous.
Structure of equine infectious anemia virus proteinase complexed with an inhibitor. Equine infectious anemia virus (EIAV), the causative agent of infectious anemia in horses, is a member of the lentiviral family. The virus-encoded proteinase (PR) processes viral polyproteins into functional molecules during replication and it also cleaves viral nucleocapsid protein during infection. The X-ray structure of a complex of the 154G mutant of EIAV PR with the inhibitor HBY-793 was solved at 1.8 A resolution and refined to a crystallographic R-factor of 0.136. The molecule is a dimer in which the monomers are related by a crystallographic twofold axis. Although both the enzyme and t...
Biochemical changes in three-day-event horses at the beginning, middle and end of Phase C and after Phase D. Blood samples were collected 12-16 h before the Speed and Endurance test, immediately after steeplechase, midway through Phase C (4 km marker), at the end of Phase C and immediately after cross-country from 36 horses that completed a 3-day-event at the CCI* (n = 19) or CCI** (n = 17) level. Packed cell volume (PCV), plasma concentrations of sodium, potassium, chloride, ionized calcium, pH and lactate; and serum concentrations of total protein (TP), albumin, total calcium, alkaline phosphatase (AP), gamma glutamyl transferase (GGT), creatine kinase (CK), aspartate aminotransferase (AST), glucos...
Effect of cycloheximide on nuclear maturation of horse oocytes and its relation to initial cumulus morphology. The period of protein synthesis necessary for meiotic maturation in horse oocytes initially having compact or expanded cumulus cells was studied. Oocytes incubated in the presence of cycloheximide after 0, 4, 8, 12 or 16 h maturation in vitro (total incubation time 24 h) were matured for 24 h, or were incubated with cycloheximide for 24 h and then matured for 24 h. Incubation with cycloheximide from 0 h was effective in suppressing maturation (no significant increase in maturing oocytes compared with controls fixed directly after removal from the follicle) in both expanded and compact groups a...
